CVE-2023-40044
About
In WS_FTP Server versions prior to 8.7.4 and 8.8.2, a pre-authenticated attacker could leverage a .NET deserialization vulnerability in the Ad Hoc Transfer module to execute remote commands on the underlying WS_FTP Server operating system.
Rainforest analyst review
Progress WS_FTP Server's Ad Hoc Transfer module deserializes attacker-supplied .NET data without validating it. A pre-authenticated attacker sends a crafted serialized object to that module, and when the server reconstructs it, a gadget chain fires that runs operating-system commands on the host. There is no login requirement, so anyone who can reach the Ad Hoc Transfer web interface can turn a single request into command execution on the underlying Windows server.
WS_FTP is a managed file-transfer product, the same category as MOVEit, meaning the data it guards is precisely the sensitive, regulated material organizations exchange, and these servers are routinely internet-facing to allow external partners to connect. That combination, pre-auth RCE on an internet-exposed file-transfer appliance, is exactly the profile ransomware and data-extortion crews have learned to hit at scale, and this flaw came from Progress in the immediate wake of the MOVEit campaign, drawing fast attention. Patch to WS_FTP Server 8.7.4 or 8.8.2 as the priority, and given how quickly proof-of-concept code circulated, review the Ad Hoc Transfer module and server for signs of exploitation rather than treating the update alone as sufficient.
References
- http://packetstormsecurity.com/files/174917/Progress-Software-WS_FTP-Unauthenticated-Remote-Code-Execution.html
- https://attackerkb.com/topics/bn32f9sNax/cve-2023-40044
- https://censys.com/cve-2023-40044/
- https://community.progress.com/s/article/WS-FTP-Server-Critical-Vulnerability-September-2023
- https://www.assetnote.io/resources/research/rce-in-progress-ws-ftp-ad-hoc-via-iis-http-modules-cve-2023-40044
- https://www.progress.com/ws_ftp
- https://www.rapid7.com/blog/post/2023/09/29/etr-critical-vulnerabilities-in-ws_ftp-server/
- https://www.theregister.com/2023/10/02/ws_ftp_update/
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-40044
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Frequently asked questions
What is CVE-2023-40044?
In WS_FTP Server versions prior to 8.7.4 and 8.8.2, a pre-authenticated attacker could leverage a .NET deserialization vulnerability in the Ad Hoc Transfer module to execute remote commands on the underlying WS_FTP Server operating system.
How severe is CVE-2023-40044?
CVE-2023-40044 carries a CVSS 3.1 base score of 10, rated critical. On the Rainforest Risk Index — which weighs the severity alongside how easy the flaw is to reach and how broad its impact is — it scores 100 out of 100, in the critical band.
How is CVE-2023-40044 exploited?
According to the CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H): attack vector Network, attack complexity Low, privileges required None, user interaction None. Impact on confidentiality High, integrity High and availability High.
Which products are affected by CVE-2023-40044?
Public advisories list the following as affected: ws ftp server. Check the references on this page for the exact versions each vendor confirms.
How do I fix CVE-2023-40044?
Apply the fix the vendor published — the references on this page link to the primary advisories and patches. When patching can't happen right away, reduce the exposure of the affected component and watch it for exploitation attempts. Rainforest customers see this vulnerability correlated to their own assets and prioritized by real exposure, not by score alone.
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